Supervisory system



o1.13,1931. M ,LNELSON 1,827,098

SUPERVI SORY SYSTEM Filed A0G15. 18. 1928 RECEIVING Patented ct. l13,

'i UNITED "STATES PATENT OFFICE MARTIN L. NELSON, OF PABX RIDGE, ILLINOIS, ASSIGNOR T RESERVE HOLDING OOM- PAN Y, OF KANSAS CITY, MISSOURI, A CORPORATION OF DELAWARE SUPERVISOBY SYSTEM Application led October 18, 1928. Serial No. 313,294.

This inventionrelates in general to super- .yvisory systems, more particularly to such systems in which remotely located stepping switches are synchronously operated, one to connect up indicating devices and the other briefly stated, is the production of a new and improved system of this type, a system particularly adapted to use in connection with carrier current systems, wherein the channel between the two devices is a carrier current channel.

Supervisory systems have been devised heretofore, most of those systems depending upon the use of one ormore physical wires between Ithe station containing the devices frequently happens,

that it is desired to supervise and the station containing the supervisory apparatus. It

articularly in telemetering work, where the devices to be supervised are meters indicating the voltage, load, or other information of a power circuit, that it is more advantageous to connect the supervisory units together through a carrier cur'- rent channel, the channel being superimposed upon the power circuit itself so that no additional conductors are' necessary between the devices. Carrier current systems are old and well known to those skilled in the art, and such systems can best be modulated by alternating current im ulses of relatively high -frequency. Accor ingly, as an object of my invention, I provide a new and improved stepping circuit for steppin switches in synchronism, a circuit in w ich the controlling impulses'are impulses of high frequency alternating current.

To be valuable the indications given by a supervisory system of the type disclosed in l this invention must be accurate.

-sitates that the stepping switches be per- This necesfectly synchronized at all times so that the indication recorded by one of the indicating devices will be the correct indication for the device that the indicator supervises. If the switches get out of synchronism, an indicator may be operated by another device whose 4.contacts appear in the banks of the selecting switches in positions adjacent tothe contacts of the device associated with the indicator. Various methods have been employed heretofore to synchronize two or more moving switches, none of these methods/'being particularly suited to systems wherein the channel between the devices is a carrierkcurrent channel. Accordingly, as a further object of my invention, I provide al 'new and improved method of synchronizing two or more stepping switches, a method adaptable for use with alternating current control.

These and other objects of the invention not specifically mentioned here, will be best understood from a reading of the detailed description and claims which follow.

The drawing shows by the usual circuit symbols sufficient apparatus to enable a clear understanding of my invention. The apparatus to the left of the dotted line in the drawinor is that located in the sending station. fn a telemetering system, for example, the sending station would be thedistant station in which is contained the electrical meters that itis desired to read. The receiving station, which is shown to the right of the dotted line, is the despatchers or supervisory station. lIn a telemetering system this station would contain indicating devices through the operation of which the data indicated by the meters in the sending station is also indif cated to the despatcher in the receiving station.

The equipment in the sending stationincludes a selector switch comprising the magnet 7, wipers 55 and 56 and the bank contacts associated therewith. This switch may be of the type of the well known rotary line switch, whose wipers have no normal position, but move in a forward direction only, the movement taking place when the magnet is deenergized rather than when the magnet is energized. Switches of this type normally have twenty-five contacts available to each of the wipers, this number mayy be increased to fifty by using two wipers disposed at 180, each wiper engaging a different row of twenty-five contacts. The selector switch is controlled by the' relays 1 to 6,

inclusive, in a manner which will be pointed out in detail hereinafter. The impulsing device 20, which is shown as a vacuum tube generator, may be any desirable form of interrupter capable of alternately opening and closing a circuit extending out from it at a definite rate of speed preferably about one cycle per second.

The square 22 shown in the sending station, is a diagrammatic representation of a carrier current transmitter comprising the carrier current generator and suitable modulating devices. Since this device forms no part of the present invention, and since the invention can be. used without this device, it is not thought that further details of this device is necessary to a clear understanding of my invention'. The square 24 also represents a carrier current transmitter, or if the system in my invention is used in a telemetering system, this device 24 might well be the telemeterin transmitter shown in the co-pending app lcation of Harold C. Pye, Serial No. 289,037, filed June 28, 1928.

The receiving apparatus at the despatchers station includes a selecting switch comprising magnet 11 and wipers 65 and 66, this switch being also of the type of the well known rotary line switch. The selecting switch is controlled by relays 8, 9, and 10 1n a manner which will be pointed out in detail hereinafter. The square 23, in' which the line from the sending station terminates, may7 be any well known carrier current demodulator, an equipment not forming an integral part of the resent invention and is not shown in detail. t' carrier current is not used and the conductor 70 is a physical conductor from the sending station to the receiving station, the square 23 needs to be only an amplifier such as is shown within the square, that amplifier including the vacuum tube 21 and suitable inductances 58 and 59 through whlch the input side of the tube is connected to the line conductor 70. The square 25 may also be a carrier current demodulator, or if the conductor 71 is a physical sender from the sender to the receiver the demodulator is not required. l

I nasmuch as my invention relates to the stepping and synchronizing of the selecting switches, I have chosen to show the invention in connection with a simple supervisory system in which the contact 57 at the sending station is moved by some electrical or mechanical movement, such as the openin and closing of a circuit breaker' for examp e, to place one or the other terminal of a supervisory battery upon a particular contact in the bank over which wiper 56 rotates. I havealso shown conductor 71 as a physical conductor connecting the wiper 56 to the wiper 66 of the receiving selector. The bank contact in the receiving selector corresponding to the bank contact 57 leads to a simple polarized relay which controls two indicating lamps 15 and 16. I have chosen this part1cular arrangement, since the type of signal transmitted over the device used to transmit it does not form an integral part of my invention. Throughout the drawing I have shown a lurality 4of battery and ground symbols. xcept where the potential of the batteries is indicated, this plurality of batteries is merely for simplification of the drawing as in an installation of the system of my invention there would be but one battery in each station, preferably of about fift volts potential. The 125-volt batteries in icated in the plate circuit of the vacuum tubes 2O and 21, could either be a suitable B battery or a B potential i source.V The filament battery shown in connection with vacuum tube 20 would be a suitable A battery 0r if desired the filament of this tube may be operated on alternating current or by any of the well known so-called A batteries eliminators.

The system as shown is a design for continuous operation, that is the selecting switches step their wipers over their respective banks continuously at a relatively slow rate of speed, that is, say one step per second. To start the system in operation, the switch 32 in the filament circuit of the vacuum tube 20 is closed to light that filament. Space current flows through the tube, through the plate of the tube, and through the winding of relay 1 to energize that relay. The energization of relay 1 at springs 41 closes a point in the circuit of relay 2 which latter relay has a copper slug on the end of its core, indicated on the drawing by the shaded portion at the upper end of the core, and is therefore slowvto pull up and does not immediately energize. A

short time after the energization of relay 1,

relay 2 pulls up closing a circuit from ground through springs 41, springs 44, spring 48 and its break Contact through the winding of the magnet 7 of the selecting switch to lbattery. The energization of relay 1 also opens a point in the circuit of wiper 56, to open the supervisory circuit during the movement of the switch wipers. The energization of relay 2 at springs 45 closes a circuit from the junction point of the filament, grid condenser, and resistance ofthe vacuum tube 20, through the grid bias battery C, through springs 45 to the junction point of the grid, grid condenser 30 and resistance 31. Negative potential from the grid bias .battery C is connected to opposite terminals of the condenser 30, to thereby bias the grid of the tube 20 strongly negative. This reduces the plate current to a point where the relay 1 deenergizes. The deenergization of relay 1 opens the circuit of the motor magnet 7 to permit that magnet to fall back4 and advance the wipers 55 and 56 of the sending switch one step. The deenergization of relay 1 opens the circuit of relay 2 which because ofthe copper slug on its core is slightly slow to release and remains enercuit from the condenser 30, andthe charge placed upon that condenser is allowed to leak oil through the high resistance 31. The rela-y tive value of this resistance with respectto the capacity of the condenser determines the period `of time that the rid of the tube will remain negatively iased, that is, the time which must elapse before sufficient plate current flows through the winding of relay l to reenergize that relay. When relay 1 again energizes, the cycle .of operations )ust enumerated is repeated, and the wipers 55 and 56 of the selecting switch are stepped over their banks in this manner.

The tone generator 18, which is shown as a simple alternator, may be any well known type of generator capable of generating a frequency of say 1000cycles. With the relays 1 and 3 both normal the tone generated by generator 18 traverses a circuit from ground through the generator 18, springs 40, 1 springs 46, over the path 70 to the winding of inductance 58 to ground. This tone induces a potential of similar frequency 1n the Winding 59, which potential'is applied to the grid of the tube 21 to control the space current flowing in that tube. As longas tone is on conductor 70 plate current will be fiowT ing from the tube 21 through the winding of relay 8, to maintain that relay energized for a purpose which will be hereinafter pointed out. When relay 1 of the sender is energized in the hereinbefore explained manner, springs open to remove the tone from the path 70.y When relay 2 energizes a moment later, springs 43 close to reapply the tone to the path 70. Thus it will be seen that each operation of the relays 1 and 2 remove the .tonel from the path 70 for a brief interval,'that interval being the length of. time which relay 2 delays in pulling up.

Referring now to the plate circuit relay 8 of the receiving mechanism, when space current is flowing that relay is energized and closes the obvious circuit through springs and the relay 9, to energize that relay. Relay 9 through spring 61 and its make contact closes the circuit of relay 10, which relay being a slow to release relay, so designatedfon the drawing by the cross-hatched sectii'in atA the lower part of its core, will'remain per? ated for a definite interval of time after th circuit through its Winding has been opened. When `the tone on the current is interrupted and no plate current flows through the relay 8 that relay falls back and opens the circuit of relay 9 which also falls back. A circuit may now be traced from ground through springs 6l and its break contact, springs 62 and its make contact, through the Winding of motor magnet 11 to battery. This magnet energizes, preparatory. to ad*- vancing the wipers 65 and 66 one step. When tone is reapplled to the path 7 0 by the energization of relay 2, relays 8 and 9 are reenergized, the latter opening the circuit of magnet 11 at springs 61. The magnet ll falls back and advances the wiper of the receiving selector one step. The stepping of the wipers 55, 56, 65, and 66 will-continue in this manner as long as the switch 32 of the impulse generator 2O remains closed.

In order to synchronize the action of the two switches, when the wiper 55 of the sender encounters contact 73 of its bank, a' circuit is closed from ground -throu h the wiper'55 and that contact and the winding of relay 6 to energize the latter relay. The energization of relay 6 at springs 54 applies a short circuit to the relay 3. That relay normally has ground connected to its upper terminal through the springs52 now also has ground connected to its lower terminal through the springs 54. Vhen the wiper 55 passes olf of the contact 73, relay 3 pulls up over a circuit including springs 52, relay 3, springs 54 and the relay 6 to battery, the relay 6 being held in its energized position through 'the' relay 3. The energization of relay 3 at springs 47 closes a point in the return-tonormal circuit of the sending selector, thatcircuit including ground through the wiper 55 and the multiplied contacts of` the bank over which that wiper passes, springs 47, interrupter springs 53, through the winding of magnet 7 to'battery. When the magnet energizes interrupter springs 53 are opened, and themagnet deenergizes to advance the wipers one step. This action continuing as long as the circuit is closed through the wiper 55 and the multiplied contacts available thereto. The energization of relay 3 at springs 48 and its make contact closes a point in the circuit of relay 4 Which relay is energized the next time therelay 1 is energized. The energization of relay 4 at springs 51 prepares a circuit for the relay 5, which relay is short circuited as long as relayl remains energized. When relay 1 deenergizes, relay 5 is energized and relay 4 locked energized over a circuit traceable from ground through springs 49, the winding of relay 5, springs 5l, the Winding of relay 4 to battery. The energization of relay 5 over, this circuit at springs 52 opens the circuit over which relays 3 and 6 were locked energized, to permit those relays to restoreto normal.

When relay 3y energized in the manner just described, at springs 46 it opens af point in the tone cireuit'to the path 70, to thereby remove the tone from that path to permit the relay 8 of the receiving mechanism to restore to normal. -Relay 8 opens a circuit of relay 9 whichsrestores to normal' and opens the circuit of relay 10. After' a' brief interval relay 10 restores to normal, thereby completing the return to normal circuit of lic lao

occupied by the wipers 65 and 66 they will A'sie be advanced to their normal position, that is the position in which they are shown in the drawing. When relay 3 falls back responsive to the energization of relays 4 and 5, wipers and 56 of the sending selector will be in their normal positions and Wipers and 66 of the receiving selector will likewise be in their normal positions and impulsing will be resumed with both switches starting from their normal position. Thus it will be seen that if the switches get out of step some# where during a half revolution over their banks, that condition will be corrected auto- -matically when the wiper 55 of the sending switch encounters the contact 73 and the 'multipled contacts adjacent thereto.

' thatspring being arranged to close against its uppermost contact when the device is in one position and against its lowermost contact when the device is in its opposite position. When wiper 56 engages the contact to which springs 57 is connected, and relay 1 has fallen back, a circuit may be traced from ground `through positive battery and resistance 12,

springs 57, wiper 56, springs 50, springs 42, over the path 71, springs 63, wiper 66 now engaging the contact to which ,relay 14 is connected, through the polarized relay 14 to ground. Relay 14 is energized over this circuit operating its armature 17 to the right to close a circuit from ground through that armature and the lamp 16 to battery, to light the lamp to indicate that the device controllingspring 57 is in the position corresponding to the uppermost position of the spring. Ifthe spring 57 moves down against its lowermost contact the same circuit is closed as before except that it extends through resistance 13 and negative battery and relay 14 is operated in the opposite direction to extinguish .the lamp 16 and to light the lam 15 to indicate that the spring has so move If carrier current devices 24 and 25 are used, the path 71 then becomes a high frequency carrier current path and the circuit closed by spring 57 controls devices to modulate that carrier, current in a` manner distinctive of the position occupied by the spring 57.

Such devices are well known to those skilled in the art and inasmuch as they do not form an integral part of the present invention further description of them is not deemed necessary to a full understanding of the operation of my invention.

While I have chosen to show my invention in connection with a particular type of apparatus, I have done so by way of example only as there are many modifications and ada tations which can be made by one skilled in tiie art without departingfrom the scope of the invention.

What I claim is; l

1. In a synchronizing system, devicesl having normal positions and stepping means, an impulse generator, circuits over which 1mpulses are transmitted by said generator tor stepping said devices, a relay associated with one of said devices, means responsive to one of said devices reaching a predetermined position for preparing a circuit to said relay, means responsive to said one device stepping off of said predetermined position for operating said relay, and means controlled by said relay for opening said impulsing' circuits and for causing said devices to return to their normal positions to synchronize them.

2. In a synchronizing system, devices having normal positions, means for stepping said devices, a relay associated with one of said devices, means responsive to one of said de vices reaching a predetermined position for preparing a circiut to said relay, means responsive to said one device stepping oit of said predetermined position for operating said relay, and means controlled by said relay for causing said devices to automatically step to their normal positions to synchronize them.

3. In a synchronizing system, devices having normal positions, means for stepping said devices, a relay associated with one of said said relay, means controlled by said relay for causing said devices to automatically step to their normal positions to synchronize them, and means for controlling said relay t0 cause said devices to be stepped in a second cycle of operation.

4. In a synchronizing system, devices each having a normal position, an impulse generator, means controlled by said generator for stepping said devices, a relay associated with one of said devices, means responsive to said one device reaching a predetermined position for preparing a circuit for said relay, means resppnsive to said device stepping off of said predetermined position for operating said relay, a local circuit in each of said devices for returnin said devices to their normal positions, an means 'controlled by said relay for closing said local circuits to cause said devices to step to their normal positions independent of said impulse generator to syn- .,chronize them. 5 5. In a synchronizing system, devices each having a normal position, an impulse gen-l erator, means controlled by said generator for stepping said devices, a relay associated with one o said devices, means responsive to said one device reaching a'predetermined position for preparing a circuit for said rela means responsive to said device stepping o of said redetermined position for operating 'said reay, a local circuit in each of said devices for returning said devices to their normal positions, means controlled by said relay for closing said local circuits to cause saiddevices to step to their normal positions independent of said impulse generator to synchronize the devices, a second relay associated with said one device, means controlled by said impulse generator for operating said second relay, and means controlled by said second rela for operating said first relay to reestablis the' stepping operation under control of said generator whereby said devices are stepped in a second cycle of operation.

In witness whereof, I hereunto subscribe my name this 12th day of October, A. D. 1928. MARTIN L. NELSON.. f 

